1. Field of the Invention
The present invention relates to a technique for generating information regarding a link structure of documents which indicates a link structure for a group of web documents and, in particular, to a technique for handling a case in which a redirection of a document is present.
2. Description of the Related Art
Web documents which exist on the World Wide Web (hereinafter simply referred to as the “WWW”) and which are written in HyperText Markup Language (“HTML”) form a network structure having each web document as a node by providing links to each other. The network structure is commonly referred to as a hypertext structure or a hyperlink structure.
Various software has been developed for diagrammatically displaying a structure of connection relationship formed by a group of such web documents through links.
For example, Japanese Patent Laid-Open Publication No. Hei 6-149648 discloses a hyper media system which can display data connected by links in units of cards wherein a network diagram is displayed in which arrows connect icons which correspond to the cards to indicate links among the cards.
Japanese Patent Laid-Open Publication Nos. Hei 4-321144 and Hei 10-222415 disclose a system in which a hypertext structure constructed by a group of documents is displayed in a form of a tree structure with each document being a node and each link being an edge of the tree.
On the WWW, there are many instances in which a web document indicated by a certain URL (Uniform Resource Locator) is redirected to a web document at another URL. A redirection is employed in cases, for example, when a web site has been moved. There are various methods of redirection, including, for example, a method for setting a redirection in the web server program itself, a method for incorporating a CGI (Common Gateway Interface) script in the web server to indicate a redirection, and a method for including a description of a redirection in the web document using a meta tag.
Consider a case as shown in FIG. 1 in which a web document B1 indicated in a link description of a web document A as a link destination is redirected to another web document B2. In such a case, the web document B1 either is only present as URL and does not have a document body or includes a simple content such as an explanation of the new URL, and thus, in general, does not have any meaningful content as a link destination. The web document B2 has the content of interest as the link destination.
However, when the related art shown in the above-described references is applied to a link structure of a group of web documents including a redirection, as shown in FIG. 2, although an arrow indicating a link from the web document A to the web document B1 is displayed, the relationship among web documents A and B2 is not displayed. In particular, when no link is described in the web document B1 to the web document B2 (for example, when redirection is set in the web server program), even the indirect link relationship from the web document A through the web document B1 to the web document B2 is not displayed in a method in which presence of inter-document link is detected from the link description within web documents.